The hypothesis of this study is that serious rotavirus infections resulting in care at a hospital have been significantly under-assessed in the U.S. The purpose of this study is to assess the impact of rotavirus infection resulting in treatment at a hospital. This study is needed to assess justification for a rotavirus vaccine in the U.S. 1. To assess the impact of rotavirus infection in hospital care for illness. 2. To assess the medical and nonmedical costs of this care.